Transmission and Drivetrain: Description and Operation
Transfer NoteNOTE: When servicing 2WD vehicles with transfer case, use the same procedure but refer to the parts diagram of 2WD vehicles at Transfer Construction: Lever-Shift Type and Transfer Components: Lever-Shift Type check their differences from 4WD vehicles.
Precautions in Diagnosing Trouble
^ Do not perform the following services before confirming diagnostic information (DTC, etc.) stored in 4WD control module memory. These actions will erase memorized information in 4WD control module memory.
- Disconnect coupler from 4WD control module
- Disconnect battery cable from battery
- Disconnect ground wire harness of 4WD control module
- Disconnect main fuse from fuse box.
^ Diagnostic information stored in 4WD control module memory can be cleared as well as checked by using SUZUKI scan tool. Before using scan tool, read its Operator's (Instruction) Manual carefully to have good understanding as to what functions are available and how to use it.
^ Be sure to read "Precautions for Electrical Circuit Service:" before inspection and observe what is written there.
Transfer Construction
WARNING: For towing the vehicle for the purpose of repair or the like, follow the towing instructions in OWNER'S MANUAL.
The aluminum transfer case directly connected to the back of the transmission contains the input gear, countershaft and gear, output rear shaft, output low gear and output front shaft (for front drive) connected by way of the hyvo-chain. The transfer has such a selective mechanism as to enable the shift control lever to make selection of high speed (direct connection with transmission output: main shaft), low speed (speed reduction by input gear, counter gear and output low gear) or neutral by way of the reduction sleeve located between input gear and output low gear, and selection of two-wheel-drive (high speed only) or four-wheel-drive (high or low speed) by way of the front drive clutch sleeve located at the center of the output rear shaft. Also, with a synchronizer installed to the front drive clutch, it is possible to change the drive mode between 2WD (high speed only) and 4WD (high speed only) even while running.
The front drive shift fork has an auxiliary spring to make a smooth shift from "4H" to "2H" possible. The case has an oil gutter and a plate at synchronizer to provide proper lubrication even under the strict conditions of use.
4WD Control System Components
4WD Control System Description
Transfer Shift Control
The 4WD control module controls the transfer shift actuator based on the signal from the 2WD/4WD switch so that the transfer is shifted to the selected position (2H, 4H, N or 4L). (Shifting to the N position requires that the switch be kept pushing for at least 5 seconds.) The transfer shift actuator consists of the transfer shift actuator motor and the transfer shift actuator motor position sensor. The 4WD control module detects the position of the actuator motor using the position sensor and controls the actuator motor running / stopping operation. Also, the transfer fork switch, 4WD switch and 4L switch that detect the each position of the front drive shift shaft and the reduction drive shift shaft are installed within the transfer assembly. The 4WD control module detects the transfer actual shift position (2H, 4H, N or 4L) by the signals from the transfer fork switch, 4WD switch and 4L switch as follows.
Relationship of transfer shift position and switches
When the transfer shift actuator motor position detected by motor sensor and transfer actual shift position detected by the above-mentioned switches match, the 4WD control module judges that the transfer shifting is complete.
Front Axle Lock / Unlock Control
The 4WD control module actuates the axle lock actuator motor on the front differential assembly. It causes the axle lock clutch and the free axle hub in the differential case assembly to be engaged (locked) detecting the 4H/4L position of the transfer or disengaged (unlocked) detecting the 2H/N position of the transfer.
Indicator Control
The 4WD control module turns on and off the 2WD/4WD indicator, 4L indicators (in the combination meter and on the "4L" switch) and the N indicator (on the "N" switch). While the transfer is being shifted, the indicator(s) corresponding to the selected switch flashes and after the transfer shift is complete, the indicators stay on and off.
Function of 4WD Control System Component
Transfer Construction
WARNING: For towing the vehicle for the purpose of repair or the like, follow the towing instructions in OWNER'S MANUAL.
Instead of the transfer shift lever assembly, the transfer has the transfer shift actuator that shift the transfer position according to the 2WD/4WD switch operation. The other components are almost the same as the lever shift type transfer. Refer to Transfer Construction: Lever-Shift Type.
4WD Control System Operation
2H (2WD High) Position
The driving force from the transmission is transmitted to the transfer input gear. As the reduction shift sleeve and transfer input gear are engaged via the reduction hub at this time, the driving force transmitted from the transfer input gear to the rear output shaft rotate them at the same speed.
On the other hand, as the front drive clutch sleeve is not engaged with the front drive sprocket, the driving force is not transmitted to the output front shaft.
4H (4WD High) Position
When 4H position is selected from 2H position by pressing the 2WD/4WD switch, the transfer shift control actuator motor runs and both reduction drive shift cam and front drive shift cam rotate in the arrow direction "C". The front drive shift shaft shifts in the arrow direction "A" by the front drive shift cam, and the front drive clutch sleeve moves in the arrow direction "B". The driving force from the transmission is transmitted from the transfer input gear to the output rear shaft, as in the case of 2H position. Also, as the front drive clutch hub and front drive sprocket are engaged via front drive clutch sleeve, the driving force is transmitted to the front drive sprocket. Then, the front drive sprocket rotates the front output shaft via the drive chain.
N (Neutral) Position
When N position is selected from 4H position by pressing the "N" switch of the 2WD/4WD switch, the transfer shift control actuator motor runs and both reduction drive shift cam and front drive shift cam rotate in the arrow direction "C". The reduction shift shaft shifts in the arrow direction "A" by rotating the reduction drive shift cam, and the reduction shift sleeve moves in the arrow "B" direction. The driving force from the transmission is transmitted to the transfer input gear. However, as the reduction shift sleeve is not engaged with the transfer input gear and output low gear, the driving force is not transmitted to the output rear shaft and the output front shaft.
4L (4WD Low) Position
When 4L position is selected from N position by pressing 4WD low switch, the transfer shift control actuator motor runs and both reduction drive shift cam and front drive shaft cam rotate in the arrow direction "C". The front drive shift shaft shifts in the arrow "A" direction by rotating reduction drive shift cam, and the front drive clutch sleeve moves in the arrow "B direction. The driving force from the transmission is transmitted to the output low gear, through the transfer input gear and the transfer counter gear with the speed reduced. At this time, as the reduction hub and the output low gear are engaged via reduction shift sleeve, the driving force is transmitted to the output rear shaft. The driving force of the output rear shaft makes the output front shaft rotate via the front drive clutch sleeve as in the case of 4H position.
4WD Control System Wiring Circuit Diagram
Terminal Arrangement of 4WD Control Module
Input / Output Signal Table of 4WD Control Module
4WD control module outputs the following signals to actuators, indicators, etc. according to the 2WD/4WD switch operation.
NOTE: All possible shift position of transfer is shown in the table.
On-Board Diagnostic System Description
For 4WD control system, 4WD control module has the following functions.
^ When ignition switch is turned ON with engine at stop, 2WD/4WD indicator (1), 4L indicators (2) (in combination meter and "4L" switch) and N indicator (3) turn on for 2 seconds in order to check operation of these indicators.
^ When 4WD control module detects any malfunction in the following area, 2WD/4WD indicator (1), 4L indicators (2) (in combination meter and "4L" switch) and N indicator (3) flash continuously and 4WD control module come into fail-safe mode. For details of fail safe mode, refer to Fail-Safe Table: Motor-Shift Type.
- "2WD
- 4WD" switch
- "N" switch
- "4L" switch
- Transfer shift actuator motor
- Transfer shift actuator motor position sensor
- Transfer fork switch
- 4WD switch
- 4WD low switch
- Front axle lock actuator
^ DTC can be checked by either one of the following ways.
- DTC can be checked by using SUZUKI scan tool (4) connected to DLC (5).
- Without using SUZUKI scan tool, DTC can be read through flashing pattern of 2WD/4WD indicator (1), 4L indicators (2) (in combination meter and "4L" switch) and N indicator (3) by shorting diagnosis connector (6).
^ When 4WD control module detects any malfunction, 4WD control module will shift automatically to either 2H or former position which is in before shifting process began.
DLC (Data Link Connector)
DLC (1) is in compliance with SAE 11962 in its installation position, the shape of connector and pin assignment.
K line (4) of ISO 9141 is used for SUZUKI scan tool to communicate with ECM (PCM), Air bag SDM, ABS control module and 4WD control module.
Transfer Symptom Diagnosis
Before attempting to repair the transfer or related components for any reason other than mechanical failure, the condition and possible causes should be identified. Transfer failures are revealed by shifting difficulties such as excessive shifting effort, gear clash or gear grinding. When any of these conditions occur, the following inspections should be made before disassembling the transfer.
1. Check transfer oil level for insufficient or incorrect oil.
Refer to Manual Transmission Gear Oil Inspection and Change: H25 Engine Model.
2. Check transfer mountings for wear or looseness.
3. Check gear shift control lever for distortion or excessive wear.
After performing the above inspections, refer to the following diagnosis table.
Gear slipping out of mesh
Gears refusing to disengage
Hard shifting
Noise
4WD Control System Check
For the details of each step, refer to Detail of 4WD Control System Check: Motor-Shift Type.
Detail of 4WD Control System Check
Step 1: Malfunction Analysis
Customer complaint analysis
Record details of the problem (failure, complaint) and how it occurred as described by the customer.
For this purpose, use of such a questionnaire form as shown in the following will facilitate collecting information to the point required for proper analysis and diagnosis.
Customer questionnaire (Example)
NOTE: The form is a standard sample. It should be modified according to conditions characteristic of each market.
Problem symptom confirmation
Check if what the customer claimed in "Customer Questionnaire" is actually found in the vehicle and if that symptom is found, whether it is identified as a failure. (This step should be shared with the customer if possible). Check 4WD control system referring to 2WD/4WD Indicator Operation Check: Motor-Shift Type and 4WD Control System Operation Inspection: Motor-Shift Type.
DTC check, record and clearance
Perform DTC Check: Motor- Shift Type, record it and then clear it referring to DTC Clearance: Motor-Shift Type. If the malfunction DTC which was once displayed and then cleared cannot be detected (indicated) again when the ignition switch is turned ON, attempt to diagnose the trouble based on the DTC recorded in this step may mislead the diagnosis or make diagnosing difficult. Proceed to Step 2 to check 4WD control module for proper self-diagnosis function. If the malfunction DTC which was once displayed and then cleared can be detected (indicated) again when ignition switch is turned ON, proceed to Step 3.
Step 2: Driving Test
Drive the vehicle at engine speed 2000 rpm or more for 5 minute and check if any trouble symptom (such as indicator flashing) exists. If the malfunction DTC is confirmed again at ignition switch ON, driving test as described is not necessary. Proceed to Step 3.
Step 3: DTC Check
Recheck DTC referring to DTC Check: Motor- Shift Type.
Step 4: Troubleshooting for DTC
According to 4WD Control System Check for the DTC confirmation in Step 3, locate the cause of the trouble, namely in a sensor, switch, wire harness, connector, actuator assembly or other part and repair or replace faulty parts.
Step 5: Check for Intermittent Problem
Check parts where an intermittent trouble is easy to occur (e.g., wire harness, connector, etc.) referring to Intermittent and Poor Connection Inspection and related circuit of trouble code recorded in Step 1 to 3.
Step 6: Visual Inspection and 4WD Control System Symptom Diagnosis
Be sure to perform visual check of the items that support proper function of the 4WD control system referring to Visual Inspection: Motor-Shift Type. Check the part of system suspected as a possible cause referring to 4WD Control Symptom Diagnosis:Motor-Shift Type.
Step 7: Final Confirmation Test
Confirm that the problem symptom has gone and the 4WD control system is free from any abnormal conditions. If what has been repaired is related to the malfunction DTC, clear the DTC once and perform test driving and confirm that no DTC is indicated.
2WD/4WD Indicator Operation Check
1. Turn ignition switch to OFF position.
2. Check that 2WD/4WD indicator turns on for about 2 seconds and then turns off.
If any faulty condition is found, proceed to 2WD/4WD Indicator Does Not Come ON at Ignition Switch ON: Motor-Shift Type, 2WD/4WD Indicator Comes ON Steady: Motor-Shift Type or 2WD/4WD Indicator Flashes Continuously while Ignition Switch is ON: Motor-Shift Type".